Method for forming a light shielding pattern

ABSTRACT

A method for forming a light shielding pattern on a substrate having a picture element pattern on its front including picture elements which have a single color or plural colors and do not contact each other includes. 
     (1) forming a photopolymerizable light shielding material layer on the front of a substrate having picture element pattern including picture elements having a single color or plural colors, 
     (2) overall exposing from the back of the substrate, 
     (3) exposing the photopolymerizable light shielding material layer through a mask which is light transmissive at portions corresponding to the periphery of the picture elements of the picture element pattern formed on the substrate and at portions at which no picture element is present, 
     (4) developing the photopolymerizable light shielding material to form the light shielding pattern, and 
     (5) subjecting the light shielding pattern formed to a side etching to remove any portion of the light shielding pattern, which overlaps with the picture elements wherein step (2) is carried out after step (1) and before step (5).

FIELD OF THE INVENTION

The present invention relates to a method for forming a colored patternhaving a light shielding pattern with a high fineness and an excellentflatness. The method according to the present invention is particularlyuseful for preparing a color filter used for a liquid crystal display.

BACKGROUND OF THE INVENTION

Methods such as a coloring method, a dye dispersion method, a printingmethod, and a transfer method are available for forming a color filterused for a color liquid crystal display. In any method, the positionaccuracy of the respective coloring patterns (for example, red, green,blue and black) is very important. Particularly in a light shieldingpattern, a so-called black matrix, the position thereof has to besettled without having spaces between the other coloring patterns.Because of that reason, at present the black matrix is formed so that itoverlaps with the other coloring patterns to some extent. The blackmatrix is formed with a Cr vapor deposition layer in some cases, butbecause of the high cost thereof, it is considered at present to use alight-sensitive resin containing a dye such as carbon black as describedin JP-A-63-314501 (the term "JP-A" as used herewith means an unexaminedpublished Japanese patent application) and JP-A-64-35417.

However, this method involves the disadvantage that the formation of acolor filter with this method creates micron-sized projections at theportion at which the black matrix and a color picture element overlap,and these projections result in causing an opposition short (shortcircuit between the opposite electrode substrates) when a liquid crystalpanel is prepared therewith.

In order to improve the above matter, there is considered the method inwhich a light shielding material layer is formed overall on the R, G andB picture elements, and then a selective etching is carried out in avertical direction to thereby form a light shielding material layer onlyat the spaces between the R, G and B picture elements, as disclosed inJP-A-2-287404.

In this method, however, etching has a selectivity in a verticaldirection, and therefore it necessary to provide a leveling layer suchas a photoresist after providing the light shielding layer in order tocompensate for the difference in the level in the light shielding layer,which is originated from the differences in R, G and B, and there isinvolved therein a disadvantage that the number of steps is increased,and it is very difficult to control the etching amount, which results ina liability to generate a pin hole.

JP-A-1-293306 describes a method in which after coating a dye dispersinglight-sensitive resin, patternwise exposing and developing, a blackresist is coated and an exposure is made from the non-coated side,followed by developing. However, it is not in any way indicated toremove an overlapped portion by side etching as in the presentinvention. Further, a black matrix having a large light shieldingperformance with a sufficient accuracy cannot be formed with the methodby back exposing described in this specification, since the exposure ofa black color light-sensitive resin from the back does not promotecuring to a sufficient depth.

JP-A-64-78221 describes a method in which after coating a coloredlight-sensitive resin on a substrate, patternwise exposing anddeveloping, an exposure is made from the substrate side. Further,JP-A-2-77702 describes a method in which a patternwise exposure is madefrom both sides of a colored resist coated side and a non-coated side ona transparent substrate. Further, JP-A-2-53003 describes a method inwhich after coating a dye dispersing light-sensitive resin, patternwiseexposing and developing, an overall exposure is made once again withoutapplying a mask.

The application of this method improves the pattern formability, but anoverlapping with the R, G and B picture elements can not be removed, andthe flatness is insufficient.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a method for readilyforming a light shielding pattern having a good flatness, no voids and ahigh shielding performance in a simple manner. The method according tothe present invention is particularly useful for preparing a colorfilter having an excellent characteristics.

The above object of the present invention has been achieved by a methodfor forming a light shielding pattern on a substrate having pictureelement patterns which have a single color or plural colors and do notcontact each other, wherein the following steps are included.

One embodiment of the present invention is a method for forming a lightshielding pattern on a substrate having a picture element pattern on itsfront comprising picture elements which have a single color or pluralcolors and do not contact each other, which includes:

(1) forming a photopolymerizable light shielding material layer on thefront of a substrate having a picture element pattern comprising pictureelements having a single color or plural colors,

(2) overall exposing from the back of the susbtrate,

(3) exposing the photopolymerizable light shielding material layerthrough a mask which is light transmissive at the portions correspondingto the periphery of the picture elements of the picture element patternformed on the substrate and at portions at which no picture elements ispresent,

(4) developing the photopolymerizable light shielding material layer toform the light shielding pattern, and

(5) subjecting the light shielding pattern formed to side etching toremove any portion of the light shielding pattern which overlaps withthe picture elements, wherein step (2) is carrid out after step (1) andbefore step (5).

Another embodiment of the present invention is a method for forming alight shielding pattern on a substrate having a picture element patternon its front comprising picture elements which have a single color orplural colors and do not contact each other, which includes:

(1) forming a photopolymerizable light shielding material layer on thefront of a substrate having picture element patterns comprising pictureelements having a single color or plural colors,

(2) exposing the photopolymerizable light shielding material layerthrough a mask which has a light transmissive region corresponding toportions at which the picture elements of the picture element patternformed on the substrate are not present,

(3) developing the photopolymerizable light shielding material layer toform a light shielding pattern which is larger than the lighttransmissive region of the mask, and

(4) subjecting the light shielding pattern formed to side etching toremove any portion of the light shielding pattern which overlaps withthe picture elements.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will be explained below in detail.

The method for forming the light shielding pattern according to thepresent invention is characterized in that by utilizing the fact that inthe black photopolymerizable light shielding material used for formingthe light shielding pattern, light does not reach sufficiently insideduring exposure, and therefore the polymerization degree at a portionfarther from a surface is low, after light shielding pattern is formedthe portion thereof which overlaps with the color picture elementpattern is removed to thereby obtain a multicolor pattern having anexcellent flatness.

There are available several methods for forming the pattern having a lowpolymerization degree at a portion far from a surface.

One is a method in which after a photopolymerizable light shieldinglayer is formed, a portion of the respective picture elements of thepicture element pattern and a portion at which no picture elements arepresent are exposed on the photopolymerizable light shielding layerthrough a light transmissive mask to form a light shielding pattern, andthen the portion of the light shielding pattern which overlaps with acolor picture element is removed, wherein an overall exposure from theback at the step (2) in the above first method may be carried out in anyorder as long as it is carried out after the step (1) and before thestep (5) (for example, step (2) can be carried out before step (3),steps (2) and (3) can be carried out simultaneously, or step (2) can becarried out after step (3); also, step (2) can be carried out betweensteps (4) and (5)). However, if the step (2) is not carried out, thelight shielding material layer on the substrate is insufficiently curedand therefore it is attacked by a processing solution at the step (5) togenerate voids, which result in lowering a light shielding performance.As another embodiment of this method, steps (4) and (5) can be carriedout sumultaneously.

A second one is a method in which only a portion which the respectivepicture elements of a picture element pattern are not substantiallypresent is exposed on a photopolymerizable light shielding material viaa light transmissive mask so that a light shielding pattern which isformed after developing becomes larger than a light transmission regionof the mask used to thereby prepare the light shielding pattern and thenthe portion of the light shielding pattern which overlaps with the colorpicture element is removed. In one particular embodiment, steps (3) and(4) of the above second method can be carried out simultaneously.

Such exposure can be carried out by methods such as making an exposureexcessive and having a slight gap between a photopolymerizable lightshielding layer and a mask without tightly contacting them.

In this second method, the polymerization degree at the portion of thelight shielding pattern which overlaps with the color picture elementsis low compared with that in the first method and it becomes possible toremove it with a weaker processing solution than that used in the firstmethod. Accordingly, while an exposure from the back is not essential, alight shielding pattern having fewer defects can be formed by anexposure from the back.

In the present invention, the procedure for removing the portion of thelight shielding material pattern which overlaps with the color pictureelements is called "side etching".

There are available various methods for carrying out the side etching,such as carrying out the processing with a solution having a compositiondifferent from that of the developing solution after developing thelight shielding material layer and extending the developing timenecessary for forming a usual pattern.

In these procedures, it is effective as well to apply the processingsolution by rubbing with a brush.

Next, the method for forming a multicolor pattern with the presentinvention will be explained.

First, the red (R), green (G) and blue (B) picture element patterns areformed on a transparent glass substrate. Any of a coloring method aprinting method, an electrodeposition method, an electrodepositiontransfer method, a transfer method, and a pigment dispersion method canbe applied as a forming method. Next, a photopolymerizable lightshielding material layer is provided overall thereon. A pigmentdispersion method or a transfer method, and a printing method such as ascreen printing method in some cases, can be used as the methodtherefor.

Further, in order to prevent the generation of pin holes, an overallexposure is given from the back to cure a part (a vicinity of thesurface on the side closer to the light source) of the light shieldingmaterial layer between the R, G and B picture elements, and then apattern exposure is given from a front side via a photomask which isdesigned so that the light shielding material layer remains in thevicinity of the R, G and B picture elements partly superposing and thespaces between the R, G and B picture elements are fully filled upwithout gaps. Then, the unnecessary portion of the light shieldingmaterial layer is removed by a development processing to thereby convertthe light shielding material layer to the pattern.

In the above procedure, projections of several μm are formed because ofan overlapping part existing between the respective R, G and B pictureelements and light shielding part. In the light shielding materiallayer, however, because of a low light transmission, aphotopolymerization usually takes place only on the surface thereof, andthe lower part is scarcely photopolymerized.

Accordingly, either a further extension of the development processing orprocessing with a solution having a different composition from that ofthe developing solution leads to subjecting the light shielding part ofan overlapping portion to side etching, and finally the projections onthe overlapping portion are removed.

The photopolymerizable light shielding material according to the presentinvention may be prepared by dispersing or dissolving carbon black, ablack pigment, a black mixture consisting of the combination of pluralcolor pigments which may include carbon black and/or a black pigment, ora black dye, in a photopolymerizable composition. The photopolymerizablelight shielding material in which carbon black, a black pigment or apigment mixture is dispersed is better in terms of providing a lightshielding layer with excellent heat resistance and light fastness.

As a photopolymerizable resin composition, one capable of beingdeveloped with an alkaline aqueous solution and the one capable of beingdeveloped with an organic solvent are available. Of them, the onecapable of being developed with an alkaline aqueous solution ispreferred in terms of safety and cost of the developing solution. Theone capable of being developed with an alkaline aqueous solutioncontains a binder having a carboxylic acid group, a polyfunctionalacrylic monomer and a photopolymerization initiator as the maincomponents.

The preferred photopolymerizable light shielding material, which isdescribed in JP-A-1-152449, is the composition containing as thepigment, carbon, titanium carbon and iron oxide singly or in a mixturethereof; as the polyfunctional acrylic monomer, methacrylates such asethylene glycol methacrylate, triethylene glycol dimethacrylate,1,3-butanediol dimethacrylate, tetramethylene glycol dimethacrylate,propylene glycol dimethacrylate, trimethylolpropane trimethacrylate,1,4-hexanediol dimethacrylate, pentaerythritol tetramethacrylate, anddipentaerythritol hexamethacrylate; as the binder having a carboxylicacid group, a copolymer of an unsaturated organic acid compound such asacrylic acid and methacrylic acid and an unsaturated organic acid estercompound such as methyl acrylate, ethyl acrylate and benzylmethacrylate; and as the photopolymerization initiator, a halomethyloxadiazole series compound or a halomethyl-s-triazine series compound.The preferred contents of the respective components in terms of % byweight based on the total solids content are about 10 to about 50% forthe pigment, about 10 to about 50% for the polyfunctional acrylatemonomer, about 20 to about 60% for the binder having a carboxylic acidgroup, and about 1 to about 20% for the photopolymerization initiator.However, the photopolymerizable composition capable of being used forthe present invention is not limited thereto and can suitably beselected from the publicly known ones.

As the method for forming the photopolymerizable light shieldingmaterial layer on the aggregate of the picture elements usuallyconsisting of the R, G and B picture elements on a glass substrate,publicly known methods such as a method in which a solution of the abovephotopolymerizable composition is coated with a coater such as a spincoater or a roll coater and dried, a method with screen printing, and amethod in which a photopolymerizable light shielding material layerformed by coating on a different temporary support and drying istransferred and laminated with a laminator are available, and thephotopolymerizable light shielding material layer can be formed withthese publicly known methods. Further, an oxygen shielding layer whichis soluble in a developing solution or water, such as polyvinyl alcohol,may be provided on the photopolymerizable light shielding layer.

Of these methods, the method involving laminating by transfer, which hassimplified steps and by which the stable performance can be obtained, ispreferred. In this method, an intermediate layer having a good peelingperformance from a temporary support can be provided between the lightshielding material layer and the temporary support. This intermediatelayer preferably consists of a material having a small oxygen permeationin order to increase the photopolymerization performance of the lightshielding material layer.

In the method for forming the light shielding pattern according to thepresent invention, an even exposure is given to an area including aregion occupied by the R, G and B picture elements at an exposing stepfrom the back after forming a photopolymerizable light shieldingmaterial layer. The maximum exposure is selected so that thephotopolymerizable light shielding material layer portion opposite to anexposed face of the R, G and B picture elements is not insolubilized inthe developing solution by a part of light transmitting through thosepicture elements. When it is not desired that the light shieldingmaterial layer is insolubilized in a region in which the R, G and Bpicture elements do not exist, an exposure from a back can be carriedout through a photomask masking the portion.

It is important to provide a minimum exposure in exposing from the backso that a photopolymerizable light shielding material layer exposed fromthe back remains on a transparent substrate at least when it isprocessed in a developing solution. In exposing from the back, anexposure can be given under a non-oxygen atmosphere such as a vacuum,nitrogen gas and argon gas, and heating can be applied in, during orafter the exposure. As the light used for exposing, light of ultravioletto visible regions can be used. Conventional lamps such as an ultra highvoltage mercury lamp, a xenon lamp, a carbon arch lamp, and an argonlaser can be used to provide the light.

In the method according to the present invention, a pattern exposure ofa photopolymerizable light shielding material layer after a backexposure may be given immediately after the back exposure or some timelater. Considering productivity, it is given preferably immediatelythereafter or several hours later. An exposure is not specificallylimited. Too much thereof badly affects the resolution of an image andthe following side etching performance, and therefore an optimumexposure is desirably selected. The same ones as described in the aboveback exposure can be applied as well for the light source and atmospherein the pattern exposure. The width of the overlapped portion of thepattern of the light shielding layer and the pattern of the R, G and Bpicture elements is preferably about 0.5 to about 10 μm. A width lessthan about 0.5 μm lowers productivity, since time is consumed foradjusting the position of a mask, and a width exceeding about 10 μm isnot preferable, since side etching performance is deteriorated.

In the method according to the present invention, the developingsolution is preferably an alkaline aqueous solution or a solutionprepared by mixing an organic solvent with an alkaline material.Suitable alkaline materials are alkaline metal hydroxides (for example,sodium hydroxide and potassium hydroxide), alkaline metal carbonates(for example, sodium carbonate and potassium carbonate), alkaline metalbicarbonates (for example, sodium bicarbonate and potassiumbicarbonate), alkaline metal silicates (for example, sodium silicate andpotassium silicate), alkaline metal metasilicates (for example, sodiummetasilicate and potassium metasilicate), triethanolamine,diethanolamine, monoethanolamine, morpholine, tetralkylammoniumhydroxides (for example, tetramethylammonium hydroxide), or tri-sodiumphosphate. A suitable organic solvent which is miscible with water ismethanol, ethanol, 2-propanol, 1-propanol, butanol, diacetonealcohol,ethylene glycol monomethyl ether, ethylene glycol monoethyl ether,ethylene glycol mono-n-butyl ether, benzyl alcohol, acetone, methylethyl ketone, cyclohexanone, ε-caprolactone, γ-butylolactone,dimethylformamide, dimethylacetamide, hexamethylphosphoramide, ethyllactate, methyl lactate, ε-caprolactam, or N-metylpyrrolidone. Apublicly known surface active agent can be added to the developingsolution. The developing solution can be used in the form of either abath solution or a spraying solution. In order to remove the non-curedportion of the photopolymerizable light shielding material layer,methods such as rubbing with a rotary brush and rubbing with a wetsponge can be combined. Usually, the temperature of the developingsolution is preferably from a room temperature to 40° C. It is possiblethat the development processing is followed by a rinsing step.

The method for removing the portion of the light shielding pattern whichoverlaps with the R, G and B picture elements may be carried outsimultaneously with the above developing step or as the step afterdeveloping.

As already described above, side etching is used to dissolve and removethe portion of the photopolymerizable light shielding material layersubjected to a pattern exposure which overlaps the color pictureelements by utilizing the insufficient curing in the vicinity of theportion at which the light shielding material and picture elements arecontacted. Accordingly, the solution used in the side etching step maybe fundamentally the same as the above developing solution, but asolution having a little lower dissolving power is preferably used. Thedissolving power can be adjusted by adjusting the concentration of thealkaline material, the concentration of the organic solvent misciblewith water, and the concentration of the surface active agent. The sideetching can be carried out in the same manner as described at thedeveloping step; a substrate to be subjected to the side etching may bedipped in a bath containing the processing solution, it may have theprocessing solution sprayed thereon, or the side etching can befavorably carried out by rubbing the substrate with a rotating brush ora sponge.

This processing can give a multicolor pattern with an excellent flatnessincluding a light shielding pattern.

EXAMPLES

The present invention will be explained below in detail with referenceto the following examples, which should not be construed as limiting thepresent invention in any way. All parts, percents, ratios and the likeare by weight, unless stated otherwise.

EXAMPLE 1

A coating solution consisting of the following composition H1 was coatedon a polyethylene terephthalate temporary support with a thickness of100 μm and dried, whereby a thermoplastic resin layer with a drythickness of 20 μm was provided.

    ______________________________________                                        Composition H1 for the thermoplastic resin layer:                             ______________________________________                                        Vinyl chloride/vinyl acetate                                                                             290.0 g                                            copolymer (weight ratio: vinyl                                                chloride/vinyl acetate = 75/25,                                               polymerization degree: about 400,                                             MRP-TSL manufactured by Nissin                                                Chemical Co., Ltd.)                                                           Vinyl chloride-vinyl acetate-maleic                                                                      76.0 g                                             acid copolymer (weight ratio: vinyl                                           chloride/vinyl acetate/maleic acid =                                          86/13/1, polymerization degree: about                                         400, MRP-TM manufactured by Nissin                                            Chemical Co., Ltd.)                                                           Dibutyl phthalate          88.5 g                                             Fluorine series surface active agent                                                                     5.4 g                                              (F-177P manufactured by Dainippon Ink                                         & Chemicals, Inc.)                                                            MEK                        975.0 g                                            ______________________________________                                    

Next, a coating solution consisting of the following composition B1 wascoated on the above thermoplastic resin layer and dried, whereby aseparating layer with a dry thickness of 1.6 μm was provided.

    ______________________________________                                        Composition B1 for the separating layer:                                      ______________________________________                                        Polyvinyl alcohol (PVA 205 manufac-                                                                      173.2 g                                            tured by Kuraray, saponification                                              rate = 80%)                                                                   Fluorine series surface active agent                                                                     8 g                                                (SURFLON S131 manufactured by Asahi                                           Glass Company, Ltd.)                                                          Distilled water            2800 g                                             ______________________________________                                    

Four color light-sensitive solutions of a black color (for a B1 layer),a red color (for an R layer), a green color (for a G layer), and a bluecolor (for a B layer) each having the composition shown in Table 1 werecoated on four sheets of the temporary support having the abovethermoplastic resin layer and separating layer, respectively, and dried,whereby a colored light-sensitive resin layer with a dry thickness of 2μm was provided.

                  TABLE 1                                                         ______________________________________                                        Composition of the coating solutions                                          for the colored light-sensitive layers                                                       Layer                                                                         R     B       G       B1                                       ______________________________________                                        Benzyl methacrylate/meth-                                                                      60 g    60 g    60 g  60 g                                   acrylic acid copolymer                                                        (mole ratio = 73/27,                                                          viscosity = 0.12)                                                             Pentaerythritol tetracrylate                                                                   43.2    43.2    43.2  43.2                                   Michler's ketone 2.4     2.4     2.4   2.4                                    2-(o-chlorophenyl)-4,5-                                                                        2.5     2.5     2.5   2.5                                    diphenylimidazole dimer                                                       Ilugazine Red BRT (red)                                                                        5.4     --      --    --                                     Sudan Blue (blue)                                                                              --      5.2     --    --                                     Copper phthalocyanine (green)                                                                  --      --      5.6   --                                     Carbon black (black)                                                                           --      --      --    5.6                                    Methyl cellosolve acetate                                                                      560     560     560   560                                    Methyl ethyl ketone                                                                            280     280     280   280                                    ______________________________________                                    

Further, a cover sheet of polypropylene (thickness: 12 μm) was contactedby pressing on the above light-sensitive resin layer, whereby the red,blue, green and black light-sensitive transfer materials were prepared.

These light-sensitive transfer materials were used to prepare a colorfilter in the following manner.

The cover sheet for the red light-sensitive transfer material was peeledoff, and the light-sensitive resin layer face was stuck on a transparentsubstrate (thickness: 1.1 mm) by pressing (0.8 kg/cm²) and heating (130°C.) with a laminator (VP-11 manufactured by Taisei Laminator Co., Ltd.),followed by peeling off the separating layer from the thermoplasticresin layer at the interface thereof to remove simultaneously thetemporary support and thermoplastic resin layer.

Next, an exposure was given, followed by developing to remove theunnecessary portion, whereby a red picture element pattern was formed ona glass substrate.

Subsequently, the green light-sensitive transfer material was stuck onthe glass substrate on which the red picture element pattern was formedin the same manner as above, followed by peeling off, exposing anddeveloping, whereby a green picture element pattern was formed.

The same procedure was repeated with the blue light-sensitive transfermaterial to thereby form the respective patterns of R, G and B on thetransparent glass substrate.

Further, a black light-sensitive resin layer was provided overallthereon with the above black light-sensitive transfer material by atransfer method.

In the above procedure, the transfer was carried out at a temperature of130° C., a pressure of 0.8 kg/cm² and a transporting speed of 0.2 m/min.In forming the patterns, the development was carried out by dipping in a1% sodium carbonate aqueous solution at 30° C. for 30 seconds.

Then, an overall exposure was given from the back, and subsequently anexposure was given from the front surface side at 200 mJ/cm² via aphotomask disposed so that the periphery of the R, G and B pictureelements and the picture element of the black matrix were superposed oneach other by 5 μm.

Next, the development was carried out by spraying a 1% sodium carbonateaqueous solution at 33° C. for 25 seconds, whereby a color filter havinga pattern with an overlapping portion was obtained.

Thereafter, rubbing with a sponge made of PVA was subsequently appliedwith the developing solution for 75 seconds to carry out side etching,whereby a color filter having no overlapped picture elements and no pinholes was obtained.

In the above procedure, the layer thicknesses of the respective R, G andB picture elements were settled at the same level, whereby the flatnessof the color filter became ±0.1 μm or less.

Further after that, ITO (a transparent electrode) was mounted toactually prepare a liquid crystal panel, whereby an excellent panelwhich was free of an opposition short was obtained.

EXAMPLE 2

The picture elements and black light-sensitive resin layer were providedoverall on the glass substrate in the same manner as Example 1.

Then, the portion having substantially no R, G and B picture elementswas exposed from a front side via a light transmissive mask. Theexposure was 400 mJ/cm².

Thereafter, the same processing as that in Example 1 was applied,whereby a color filter having no pin holes and an excellent flatnesssimilarly to Example 1 was obtained.

Further after that, ITO (a transparent electrode) was mounted toactually prepared a liquid crystal panel, whereby an excellent panelwhich was free of an opposition short was obtained.

EXAMPLE 3

The same procedure as in Example 1 was repeated but using a 0.5% sodiumcarbonate aqueous solution in the side etching process. The resultingcolor filter had a flatness of ±0.05 μm or less.

Further after that, ITO was mounted to prepare a liquid crystal panel.The panel prepared was excellent in that no opposition short occurred.

EXAMPLE 4

The same procedure as in Example 2 was repeated but using a 0.5% sodiumcarbonate aqueous solution in the side etching process. The resultingcolor filter had a flatness of ±0.05 μm or less.

Further after that, ITO was mounted to prepare a liquid crystal panel.The panel prepared was excellent in that no opposition short occurred.

COMPARATIVE EXAMPLES 1 AND 2

Light shielding patterns were prepared in the same manner as Examples 1and 2 except that the side etching was not carried out. In these cases,the projections present at the portion at which the picture elementswere superposed were at the level of slightly more than ±1 μm.

This color filter was used to prepare the same liquid crystal panel asthat in Example 1 to find that an opposition short was generated.

COMPARATIVE EXAMPLE 3

The black light-sensitive resin layer was similarly laminated on the R,G and B picture elements which were prepared in the same manner asExample 1. The portion having substantially no R, G and B pictureelements was exposed from the front side via a light transmissive mask,followed by carrying out the development and side etching in the samemanner as Example 1 except that the exposure from the back was notcarried out, so that not only the overlapped portion was removed butalso the other portions in the light shielding pattern were abraded, andtherefore only a light shielding pattern of a low quality having a lowoptical density and many pin holes was obtained.

COMPARATIVE EXAMPLE 4

The black light-sensitive resin layer was similarly laminated on the R,G and B picture elements which were prepared in the same manner asExample 1. After giving an overall exposure from the back, thedevelopment was carried out in a developing solution. A light shieldingpattern portion which was not sufficiently cured was subjected to alayer abrasion, and therefore only a light shielding pattern of a lowquality having a low optical density and many pin holes was obtained.

It is possible according to the present invention to prepare a colorfilter with a light shielding pattern having no overlapped pictureelements and no pin holes as well as a sufficient light shieldingperformance by a simple method.

While the invention has been described in detail and with reference tospecific embodiments thereof, it will be apparent to one skilled in theart that various changes and modifications can be made therein withoutdeparting from the spirit and scope thereof.

What is claimed is:
 1. A method for forming a light shielding pattern ona substrate having a picture element pattern on its front comprisingpicture elements which have a single color or plural colors and do notcontact each other, said method comprising in order:(1) forming apicture element pattern on the front of a substrate, said pictureelement pattern comprising picture elements having a single color orplural colors, (2) forming a photopolymerizable light shielding materiallayer on the front of the substrate having a picture element patterncomprising picture elements having a single color or plural colors, (3)exposing the photopolymerizable light shielding material layer through amask which is light transmissive at portions corresponding to theperiphery of the picture elements of the picture element pattern formedon the substrate and at portions at which no picture element is present,(4) developing the photopolymerizable light shielding material layer toform the light shielding pattern, (5) overall exposing from the back ofthe substrate, and (6) subjecting the light shielding pattern formed toside etching to remove any portion of the light shielding pattern whichoverlaps with the picture elements, wherein the side etching is carriedout with a solution having a lower dissolving power than that of adeveloping solution used in the developing of the photopolymerizablelight shielding material layer.
 2. A method for forming a lightshielding pattern on a substrate having a picture element pattern on itsfront comprising picture elements which have a single color or pluralcolors and do not contact each other, said method comprising:(A) forminga photopolymerizable light shielding material layer on the front of asubstrate having picture element patterns comprising picture elementshaving a single color or plural colors, (B) exposing thephotopolymerizable light shielding material layer through a mask whichhas a light transmissive region corresponding to portions at which thepicture elements of the picture element pattern formed on the substrateare not present, (C) developing the photopolymerizable light shieldingmaterial layer to form a light shielding pattern which is larger thanthe light transmissive region of the mask, and (D) subjecting the lightshielding pattern formed to side etching to remove any portion of thelight shielding pattern which overlaps with the picture elements.
 3. Amethod of claim 2, wherein the steps (C) and (D) are carried outsimultaneously.
 4. A method of claim 1, wherein the photopolymerizablelight shielding material layer is formed by a layer transfer method. 5.A method of claim 2, wherein the photopolymerizable light shieldingmaterial layer is formed by a layer transfer method.
 6. A method ofclaim 1, wherein the photopolymerizable light shielding material layercomprises a photopolymerizable resin composition which is capable ofbeing developed with an alkaline aqueous solution.
 7. A method of claim1, wherein the photopolymerizable light shielding material layercomprises 10 to 50% by weight of pigment, 10 to 50% by weight of apolyfunctional acrylate monomer, 20 to 60% by weight of a binder havinga carboxylic acid group, and 1 to 20% by weight of a photopolymerizationinitiator, based on the total solids content of the photopolymerizablelight shielding material layer.
 8. A method of claim 1, wherein thelight shielding pattern overlaps with the picture elements by 0.5 to 10μm at each overlap.
 9. A method of claim 1, wherein the developing iscarried out with a developing solution at a temperature of from roomtemperature to 40° C.
 10. A method of claim 1, wherein the side etchingis carried out by rubbing the substrate with a rotating brush or asponge.
 11. A method of claim 2, wherein the photopolymerizable lightshielding material layer comprises a photopolymerizable resincomposition which is capable of being developed with an alkaline aqueoussolution.
 12. A method of claim 2, wherein the photopolymerizable lightshielding material layer comprises 10 to 50% by weight of pigment, 10 to50% by weight of a polyfunctional acrylate monomer, 20 to 60% by weightof a binder having a carboxylic acid group, and 1 to 20% by weight of aphotopolymerization initiator, based on the total solids content of thephotopolymerizable light shielding material layer.
 13. A method of claim2, wherein the light shielding pattern overlaps with the pictureelements by 0.5 to 10 μm at each overlap.
 14. A method of claim 2,wherein the developing is carrried out with a developing solution at atemperature of from room temperature to 40° C.
 15. A method of claim 2,wherein the side etching is carried out with a solution having a lowerdissolving power than that of a developing solution used in thedeveloping of the photopolymerizable light shielding material layer. 16.A method of claim 2, wherein the side etching is carried out by rubbingthe substrate with a rotating brush or sponge.